Tilt pad bearings are used to support a rotating shaft within a turbomachine, such as a turbine or a compressor. Tilt pad bearings include a bearing cage and one or more pads that are coupled to the bearing cage through a pivot. The pads are adapted to contact and support the shaft, and the pivot enables the pads to move or “tilt” when supporting the shaft to prevent pad edge loading. When the rotating shaft contacts the pads, heat is rapidly generated due to the friction between the shaft and the pads. Lubricating fluid, such as oil, is often injected between the shaft and the pads to reduce the friction, and the associated heat, between the two components.
Oil injectors are oftentimes positioned between adjacent pads. When positioned in this manner, however, the oil injectors restrain the circulation of lubricant behind the pads, thus limiting the desired cooling effect to this region of the pads. To counteract this, other bearing designs include a small pipe that extends from the bearing cage through an edge of the pad and provides lubricant to the inner surface of the pad. The pipe, however, tends to reduce the ability of the pads to move freely on their pivots.
What is needed, therefore, is a practical approach for providing lubricant to the tilt pads of a bearing without restricting the range of motion of the pads.